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The study was approved by the Regional Ethics Committee, Stockholm, Sweden (reference number 2013/862-31/5). The requirement for informed consent was waived because the study was register based and the included individuals were not identifiable at any time.

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All authors declare no support from any organization for the submitted work. Dr. Fernández de la Cruz receives royalties for contributing articles to UpToDate, Wolters Kluwer Health, unrelated to this work; Prof. Mataix-Cols receives royalties for contributing articles to UpToDate, Wolters Kluwer Health, and fees for editorial work from Elsevier, unrelated to this work. All other authors declare no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years.